Excitation Functions for the Production of Fission Isomers in Various Am Isotopes

Excitation functions for the population of shape isomers in americium nuclei have been studied by triton and proton bombardment of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{242}{}_{}{}^{}\mathrm{Pu}$, and ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$ with triton energies ranging from 10 to 16 MeV and proton energies from 9 to 16 MeV. The reactions studied are ($t, 2n$), ($t, 3n$), and ($p, 2n$) leading to final nuclei ${}_{}{}^{241,243,245}{}_{}{}^{}\mathrm{Am}$, ${}_{}{}^{240,242,244}{}_{}{}^{}\mathrm{Am}$, and ${}_{}{}^{238,239,241,243}{}_{}{}^{}\mathrm{Am}$, respectively. In two cases half-lives were obtained, namely, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}(p, 2n){}_{}{}^{239m}{}_{}{}^{}\mathrm{Am}$, $T_{\frac{1}{2}}=163\mathrm{}\pm 12$ nsec and ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}(t, 2n){}_{}{}^{245m}{}_{}{}^{}\mathrm{Am}$, $T_{\frac{1}{2}}=390\mathrm{}\pm 70$ nsec.